Motor fuels



United States Patent 3,168,385 MQTOR FUELS John J. Giammaria and Henry D. Norris, Woodbury, N..I., assignors to Socony Mobil Oil Company, Inc, a corporation of New York No Drawing. Filed July 12, 1961, Ser. No. 123,419 6 Claims. (Cl. 44-66) The present invention relates to new and improved fuel compositions having a relatively high octane number and, more particularly, to such compositions containing antiknock additives and other addition agents that further improve, or appreciate, the anti-knock qualities thereof.

As is well known to those skilled in the art, octane level requirements for gasolines have been steadily rising to a level that approaches 100 ON. and higher. To some extent, octane requirements have been met by special refining methods, such as catalytic reforming. Higher octane numbers have also been achieved by the addition of anti-knock agents. In order to achieve octane ratings in the order of 100 ON, however, resort has been made to a combination of reforming plus addition of an antiknock agent. If further octane improvement or appreciation is required, severe reforming can be used, but it is very expensive. Another alternative is to increase the amount of anti-knock agent but, in the case of many antiknock agents, such as tetraethyl lead, additional amounts give less octane improvement per incremental amount. Thus, being expensive, such usage of lead-containing antiknock agents for obtaining octane numbers in the order of 100 or more is at a high cost per octane number.

It has been proposed to increase the octane rating of certain gasolines by adding relatively inexpensive materials to a fuel containing anti-knock agents so as to increase the octane rating without using additional expensive anti-knock agent. Such materials, which for convenience herein are called anti-knock appreciators, include esters of Weak organic carboxylic acids as disclosed in British Patent No. 866,610. In that patent, it is disclosed that the esters of weak carboxylic acids, such as t-butyl acetate, appreciate the octane number of certain leaded gasolines that must contain at least 10% aromatic and/or olefin content in order for the appreciator to be effective. Otherwise, and as to a gasoline consisting essentially of saturated aliphatic hydrocarbons, the appreciators disclosed in the British patent are specifically set forth as having no effect on octane improvement even though a lead antiknock agent is present. As is more specifically shown in the British patent, in Table V thereof, an isobutane-isobutylene alkylate containing 3 cc./U.S. gallons of TEL was not affected by use of t-butyl acetate as an octane appreciator.

It has now been found that in a motor fuel in the gasoline boiling range (e.g., about 75 F. to about 450 F.) consisting essentially of saturated aliphatic hydrocarbons and a small but anti-detonant amount of tetraethyl lead, the alkyl esters of weak organic monocarboxylic acids appreciate the octane number of the leadcontaining saturated aliphatic hydrocarbon fuel if a dialkyl ether is blended with the fuel. Such a discovery is not only a marked improvement in that it enables obtainment of octane appreciation with leaded base stocks (saturated aliphatic hydrocarbons) for which the art has shown ineffective results with the alkyl esters of weak monocarboxylic acids but, of considerable importance, the present invention enables the production of leaded motor fuels, based on saturated aliphantc hydrocarbons, that can be appreciated to octane numbers of at least 100 and to even 110 or more by use of alkyl esters of weak monocarboxylic acids as appreciators. As is shown more fully hereinafter, practice of this invention enables the provi- 3,168,385 Patented Feb. 2, 1965 sion of such exceptionally high octane number gasolines by use of TEL-containing blend of a saturated aliphatic hydrocarbon base stock (e.g., alkylate) and a dialkyl ether, the octane number of which blend is appreciated by an alkyl ester of a weak organic monocarboxylic acid. Moreover, and as is apparent from the herein-described invention, it enables the provision of motor fuels of exceptionally high octane number from saturated aliphatic hy-v drocarbons without requirements for presence of high octane components of the aromaticand olefinic-type hydrocarbons.

In reference to the saturated aliphatic hydrocarbon base stock of the novel fuel embodied herein, particularly suitable are hydrocarbon fractions in the'gasoline boiling range that are composed or substantially composed of branched chain saturated aliphatic hydrocarbons and, preferably, have a high octane number, such as in the order of a clear octane number of at least 80, and more preferably, 90 or more. Particularly suitable for practice of this invention are the so-called alkylates, known to those skilled in the art, that are mainly composed of highly branched paraflins such as, highly branched octanes, highly branched heptanes, highly branched nonanes, mixtures thereof, and others. Such alkylates can be prepared by any of several methods known to those skilled in the art, inclusive of which are the alkylation of isobutane with butylenes, alkylation of isoamylene with propenes, and the like, by processes using alkylation catalysts such as sulfuric acid, hydrofluoric acid and others. Thus as used herein, the term alkylate includes not only compositions of branched chain parafiins as aforesaid, but also 2, 3, 4- trimethylpentane, commercial isooctanes comprising primarily trimethylpentanes and, more specifically, alkylate produced by commercial methods by alkylation of isobutane with butylene and, still more specifically, such an alkylate having a research octane number (clear) of at least and boiling in the gasoline boiling range.

The ether component 'of the fuel compositions embodied herein are the dialkyl ethers of the formula R-O-R wherein R and R are the same or different alkyl radicals and which boil at a temperature in the boiling range of gasoline. For use in practice of this invention, the stated ethers should contain a total of at least four as the sum of the carbon atoms in the two alkyl groups and, desirably, not more than 10. Examples of such ethers include diisopropyl ether, t-butyl methyl ether, di-n-propyl ether,

amyl ethyl ether, t-butyl ethyl ether, and the like.

As aforesaid, the novel compositions embodied herein contain tetraethyl lead as the anti-knock agent, but if desired, other lead-containing anti-knock agents may be present in addition to the tetraethyl lead. Examples of such other lead-containing anti-knock agents include tetramethyl lead and tetrapropyl lead.

The anti-knock appreciators contemplated for use in practice of this invention are t-alkyl esters of weak organic monocarboxylic acids; more particularly, the tertiary alkyl esters of aliphatic monocarboxylic acids of two to eight carbon atoms, as for example, the tertiary alkyl esters of acids such as acetic acid, propionic acid, caproic acid, 2-ethyl hexanoic acid, and the like; and still more specifically, such esters of saturated aliphatic hydrocarbon monocarboxylic acids of from two to four carbon atoms; and the tertiary alkyl esters of benzoic acid. As to the tertiary alkyl group of the esters embodied for use herein, examples thereof include t-butyl, t-amyl, t-octyl and more specifically, a t-alkyl group of four to eight carbon atoms. Thus, specific embodiments of such esters include t-butyl acetate, t-amyl caproate, toctyl acetate, t-butyl benzoate, and the like. Particularly preferred for practice of this invention are the t-butyl hydrocarbon monocarboxylic acids of two to four carbon atoms and, for example, t-butyl acetate.

In, general, the compositions .of this invention com- 4 poses of illustration by use of the novel combination of the defined hydrocarbon base stock-dialkyl ether blend, tetraethyl lead and an appreciator, the compositions embodied herein maycontain other additives designed to (D-908). 2 TEL=Tetraethyl Lead. 3 TML=Tetramethy1 Lead.

, blend (Ex. 4) containing TML as the sole anti-knock agent. However, as shown for Ex. Nos. 5-8, inclusive, for the compositions containing the component combination of this invention (alkylate-ether, TEL and the defined appreciators) the appreciator substantially increased the octane number even at the high octane levels shown for the base fuel.

Although the invention has been described for purprise a saturated aliphatic hydrocarbon base stock in the 5 impart other improved properties. Thus, the composigasoline boiling range blended with an ether, as aforetions may contain anti-rust agents, metal .deactivators, defined, in whichthe'base stock may comprise from about dyes, anti-oxidants, detergents, etc.

50% to about 95% by. volume of the blend, tetraethyl Although the present invention has been described with lead in a small amount sufliicent to increase the antipreferred embodiments, it is to be understood that modiknock characteristics of the blend, and preferably from fications and variations may be resorted to, withoutdeabout one to aboutfour milliliters'of tetraethyl lead per parting from the spirit and scope of this invention, as gallon of theblend, and a small amount, sufficient to those skilled in the art will readily understand. Such appreciate the octane number of such av lead-containing V variations and modifications are considered to be within blend, of an octane appreciator as hereinbefo're defined. the purview andscopeof the appended claims. More specifically, the appreciator is used in an amount What is'claimed' is: vof'from about one to about 50 grams, and still more pref- 1. A motor fuel blend of from about 50 to about 95% erably, about five to about 25 grams per gallon of the by volume of a saturated aliphatic hydrocarbon base blend. a stock in the gasoline boiling range and from about 5 In order to further describe the invention, the followto about 50% of a dialkyl ether containing from 4 to ing tabulationcontains several embodiments of this in- 10 as the sum of the carbon atoms in the two alkyl vention as well as', for. comparison purposes, compargroups, containing a small amount, sufiicient to increase able compositions but in which a dialkyl ether or tetrathe anti-knock characteristics of said blend, of tetraethyl ethyl lead was not used. The unexpected improvement lead, and from about one to about fifty grams, per gallon in octane appreciation by use of aYdialkyl ether-alkylate ofsaid blend and sufficient to appreciate the octane numblend containing both TEL (tetraethyl lead) and .the ocber of said blend containing the tetraethyl lead, of a tane appreciators is evident from the extent of octane I tertiary C to C alkyl ester of a C2 to C organic mono increase shown in the tabulation for the embodiments carboxylic hydrocarbon acid. of this invention. It has been found, statistically, that 2. A motor fuel, as defined in claim 1, wherein the the R.O.N. can vary somewhat at the high octane level saturated'aliphatic hydrocarbon base stock has a Research from test to test, and that an O.N. improvement of at least Octane Number of at least 80, the tetraethyl lead is pres- 0.6 O.N. in duplicate tests was necessary to be signifi- :ent in an amount of from about one to about four millicant. Accordingly, an appreciator that does not appreliters per :gallon of. the blend of base stock and ether, ciate O.N. by at least 0.6 0. N. or more is not considered and the tertiary alkyl ester of an organic monocarboxylic to be effective. V acid is present in an amount of from about one to about The base stock used for the composition of the exfifty grams per gallon of said blend. amples in the tabulation was an isobutane-butylene al- 3. A motor fuel, as defined in claim 1, wherein the kylate having a Reid Vapor Pressure of 7.5 lbs. and the tertiary alkyl ester of an organic monocarboxylic acid following distillation points: 10% at 150 F., at is a tertiary C to C alkyl ester of a C to C saturated 216 F., 90% at 236 F. and an end boiling point of aliphatic hydrocarbon monocarboxylic acid. 305 F. 1 i 40 4. A'motor fuel, as defined in claim' 1, wherein the a Research. Research Example Percent Ether in Anti-Knock Agent Octane Octane Appreclator, Octane Number Allcylatetby volume) (grams/gal. of Pb as No. of Base 25.0 gJgal. No. 1 In- TEL or TML) Fuel crease with Appreciator 1.- None None 0.0 2.- .do 3.18 (TEL) 0.4 3-- ao 3.18 2313:3331:fflfdi i ffiiifllfiiifi it? Eran I 115 6 10% diisopropyl ether- 3.18 (TEL) 1.4 7 10%t-but 1 methyl 3.18 (TEL) 0.7 8 20% ii liutyl methyl 3.18. (TEL) 112.5 t-butylbenzoate-(12.5 1.2

" ether. h g.lgal.).

1 A.S.T.M. Research Method a tertiary allryl ester of an organic monocarboitylic hydrocarbon acid is a t-alkyl ester of benzoic acid in which the t-alkyl group contains four to eight carbon atoms.

5. 'A motor fuel, as defined in claim 1, wherein the base stock is an alkylate, the ether is a member from the group consisting of diisopropyl ether and t-butyl methyl ether, and the tertiary alkyl ester of an organic monocarboxylic hydrocarbon acid is a member from the group consisting of t-butyl acetate and t-butyl benzoate.

6. A motor fuel blend, by volume, of from about 50 to about 95 of an alkylate in the gasoline boiling range from about 5 to about 50% of a diallryl ether from the group consisting .of diisopropyl ether and t-butyl methyl ether, said alkylate having a Research Octane Number of at least clear, from about one to about four milliliters of tetraethyl lead per gallon of said blend, and from about one to about fifty grams, per gallon of said 5 6 blend, of an ester from the group consisting of t-butyl 2,409,746 Evans et a1 Oct. 22, 1946 acetate and t-butyl benzoate. 3,009,793 Eckert et al. Nov. 21, 1961 References Cited in the file of this patent FOREIQITI PATENTS UNITED STATES PATENTS 5 504,837 Great Bntaln May 2, 1939 OTHER REFERENCES 2,046,243 Buc June 30, 1936 2,209,204 McCulloch et al July 23, 1940 Improved Motor Fuels Through Selective Blending, 2,210,942 Lipkin Aug. 13, 1940 by Wagner et al., paper presented at 22nd Annular Meet- 2,334,006 Holm Nov. 9, 1943 ing of American Petroleum Institute, November 7, 1941;

2,384,866 Wiczer Sept. 18, 1945 m 19 p g s. 

1. A MOTOR FUEL BLEND OF FROM AOBUT 50 TO ABOUT 95% BY VOLUME OF A SATURATED ALIPHATIC HYDROCARBON BASE STOCK IN THE GASOLINE BOILING RANGE AND FROM ABOUT 5 TO ABOUT 50% OF A DIALKYL ETHER CONTAINING FROM 4 TO 10 AS THE SUM OF THE CARBON ATOMS IN THE TWO ALKYL GROUPS, CONTAINING A SMALL AMOUNT, SUFFICIENT TO INCREASE THE ANTI-KNOCK CHARACTERISTICS OF SAID BLEND, OF TETRAETHYL LEAD, AND FROM ABOUT ONE TO ABOUT FIFTY GRAMS, PER GALLON OF SAID BLEND AND SUFFICIENT TO APPRECIATE THE OCTANE NUMBER OF SAID BLEND CONTAINING THE TETRAETHYL LEAD, OF A TERTIARY C4 TO C8 ALKYL ESTER OF A C2 TO C8 ORGANIC MONOCARBOXYLIC HYDROCARBON ACID. 